JPH09155204A - Metallic carrier having elasticity holding member on outer periphery of honeycomb body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic carrier having an elasticity holding member on the outer periphery of a honeycomb body, which is increased in joining strength, by increasing the surface area of the honeycomb body or the holding member to enlarge the contact area between both. SOLUTION: The honeycomb body is formed by laminating and winding a flat plate 2a composed of a heat resistant metallic foil and a corrugated plate 2b formed by working the flat plate 2a into corrugated state so that the outermost periphery of the honeycomb body is constituted of the corrugated plate 2b and covering the outermost peripheral corrugated plate with the elasticity holding member 3 and the metallic carrier composed of the honeycomb body having the elasticity holding member 3 on the outer periphery is obtained by putting the honeycomb body in a casing. The outermost peripheral surface of the honeycomb body 2 is preferably enlarged by forming a roughened surface by a wash coat or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst-carrying metal carrier for purifying automobile exhaust gas, and more particularly to a structure of a metal carrier which is housed in a casing via an elastic holding material without using a metal outer cylinder. It is a thing.

[0002]

2. Description of the Related Art As a catalyst carrier installed in an exhaust system for purifying exhaust gas of an automobile, a metal body is used instead of a ceramic body for supporting a catalyst. Is also increasing.

Originally, a ceramic honeycomb body is loaded and supported in a metal casing connected to an exhaust gas system after carrying a catalyst. At this time, the honeycomb body is placed in a gap formed between the casing and the honeycomb body. A holding material that supports and cushions the collision with the casing is interposed.

When the temperature of the exhaust gas system becomes high during practical use, that is, during engine operation, the casing thermally expands. On this occasion,
Since the ceramic honeycomb body does not expand thermally, the gap between the ceramic honeycomb body and the casing becomes large, and when the filled holding material is made of a material that does not expand thermally, a clearance is generated, from which the gas through which raw exhaust gas passes Problems such as leakage occur. Therefore, in order to prevent gas leakage and the like, it is necessary to use a material having a thermal expansion property as the filler. However, when the coefficient of thermal expansion of the filler is higher than that of the casing, the honeycomb body is subjected to surface pressure, but since the strength of the ceramic honeycomb body does not decrease much even at high temperatures, there is no risk of collapse. .

In this way, the ceramic honeycomb body is supported by the exhaust gas system. However, the opening area of the cells of the honeycomb body, through which the exhaust gas is passed due to the material of the ceramic, cannot be increased so much, so that there is a problem of pressure loss to the exhaust gas. Occurs.

On the other hand, the honeycomb body constituting the metal carrier is formed by stacking a thin flat plate (foil) made of a heat-resistant metal and having a plate thickness of about 50 μm or less and a corrugated corrugated foil and spirally winding them. Since it is formed as described above, the opening area (porosity) of the cell can be made larger than that of the ceramic honeycomb body, and it is advantageous in terms of pressure loss and impact resistance, which are problems.

Usually, as shown in FIG. 5, the metal honeycomb body 10 is prepared by inserting a metal carrier into a heat-resistant metal outer cylinder 11 having a thickness of about 1 to 2 mm and joining and fixing it by brazing. Since the outer cylinder is exposed to the outside air and the amount of heat radiation is large, there is a difference in thermal expansion at high temperature, and thermal strain may occur, which may lead to damage of the honeycomb body.

Therefore, without using an outer cylinder, a metal honeycomb body coated with a holding material such as a ceramic fiber is directly charged and supported in the casing, and the gap between the honeycomb body and the casing is sealed without using the outer cylinder. The structure is presented.

However, since the strength of the honeycomb body itself is not so large, when the honeycomb body is covered and supported by the holding material, the tightening force cannot be increased,
In addition, the frictional resistance of the surface is lower than that of the ceramic honeycomb body, so that the holding material may be displaced due to vibration during engine operation.

In order to prevent such a problem, JP-A-5-317727 proposes a catalytic converter in which a seal material and a metal carrier are firmly bonded. That is, as shown in FIG. 4, in a metal-supported catalyst (honeycomb body) 10 in which an active alumina layer is formed except for the outermost peripheral surface, the outermost peripheral surface is covered with a ceramic sealing material 12 and then heated to heat the honeycomb body. This is a catalytic converter in which alumina whiskers are grown on the outermost peripheral surface and the ceramic sealing material 12 and the alumina whiskers are integrally bonded.

However, in order to grow the alumina whiskers on the surface of the ferrite alloy containing 5% Al constituting the metal carrier to the extent that the sealing fibers are taken in, 9
It is necessary to oxidize and bake at 00 ° C to 1000 ° C for several hours. The oxidation treatment after forming the honeycomb body is not a preferable treatment because the aluminum of the metal carrier material is consumed.

[0012]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the problems of the prior art as described above. By increasing the surface area of the honeycomb body or the holding material to increase the contact area between them, An object of the present invention is to provide a metal carrier having an elastic holding member on the outer periphery of a honeycomb body having high bonding strength.

[0013]

In order to achieve the above object, the present invention has the following structures. That is, a flat plate made of a heat-resistant metal foil and a corrugated plate obtained by processing the flat plate into a corrugated plate are overlapped and wound to form a spiral body, and the outermost periphery of the honeycomb body is formed of the corrugated plate. A metal carrier having an elastic holding member on the outer circumference of the honeycomb body, characterized in that the outermost corrugated plate is covered with an elastic holding member, and the outermost peripheral surface of the honeycomb body has a surface area which may form a rough surface. Although there are various methods for obtaining this rough surface, it is more preferable to attach activated alumina to the surface by a wash coat. This rough surface is not limited to the outermost peripheral surface of the honeycomb body, but may be formed on the elastic holding portion surface or the casing inner surface. As described above, in the present invention, by loading the honeycomb body supporting the catalyst and coating the elastic holding member into the casing, the holding member is elastically always provided between the honeycomb body and the casing (gap). And it becomes a state of being filled so as to be embedded in the valley portion of the corrugated plate that constitutes the outermost peripheral surface of the honeycomb body, and further, one or both of the outermost peripheral surface of the honeycomb body, the elastic holding member surface, or the casing inner surface. Since the surface is roughened and the surface area is enlarged, it is possible to obtain a metal carrier which has a high contact strength in both the rotation direction and the axial direction, and which reliably holds the honeycomb body.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 shows a perspective view of the present invention.
The metal carrier 1 of the present invention is composed of 2 honeycomb bodies and 3 elastic holding members. The honeycomb body 2 is formed by stacking a flat foil (flat plate) 2a made of a heat-resistant metal and a corrugated plate 2b formed by corrugating the flat plate 2a in a spiral shape and winding them in a spiral shape. There is one feature of the present invention in that the corrugated plate 4 is formed on the outermost peripheral surface in forming the spiral honeycomb body. That is, in the honeycomb body 2 of the present invention, the overlapping of the flat plate and the corrugated plate when manufacturing the conventional honeycomb body is reversed,
It can be manufactured by winding the outermost circumference only with a corrugated plate. In addition, the contact portion between the flat plate 2a and the corrugated plate 2b is joined by brazing material or heat diffusion at an appropriate place.

The honeycomb body 2 is covered with the elastic holding member 3 so as to bite into the corrugated plate 4 wound around the outermost periphery of the honeycomb body 2, and is in contact with a wide area to increase the friction resistance. As the elastic holding member 3, non-heat-expandable fibers such as alumina fibers, ceramic fibers, and mullite fibers can be used in a mat shape. Of course, the material is not limited to this, and heat-expandable fibers can be used.

FIG. 2 is a sectional view showing a state in which a casing 5 is inserted to connect the metal carrier 1 of the present invention to an exhaust gas system. There is a gap 6 between the honeycomb body 2 and the casing 5, and the elastic holding member 3 is filled in a sufficient amount to fill the gap 6 including the valley portion of the outermost corrugated plate. Reference numerals 5a and 5b are flanges that connect the casing 1 to the exhaust system.

FIG. 3 shows another example of the present invention. The honeycomb body 2 in this example is not limited to the one in which the outermost periphery shown in FIG. 1 is wound around a corrugated plate, but can be a honeycomb body formed of a flat plate. (A) The figure shows the outermost peripheral surface 4 of the honeycomb body 2 with the rough surface 7
It is formed in a and the surface area is enlarged. As a specific method for forming a rough surface on the metal surface, it is preferable to adopt a so-called wash coating method in which a honeycomb body is immersed in an alumina slurry, dried and fired to deposit the activated alumina in a concavo-convex shape. Usually, a jig for preventing adhesion to the outer periphery of the honeycomb is used for wash-coating only the inside of the honeycomb body, but in the case of the present invention, such a jig is not necessary and the wash-coating process is simplified. Further, the object can be achieved without adding a new step for roughening, which is preferable.

In FIG. 1B, the surface of the elastic holding member 3 is a rough surface 7.
b. This also makes it possible to increase the contact area with the honeycomb body. In the diagram (c), the outermost peripheral surface of the honeycomb body 2 and the inner surface of the casing 5 are roughened surfaces 7a and 7c, respectively. This can prevent relative movement between the casing 5 and the elastic holding member 3.

[0019]

【Example】

[Example 1] As shown in Fig. 1, a thickness of 5 made of heat resistant steel
A 0 μm flat foil and a corrugated box are overlapped and wound, and a honeycomb body with a diameter of 80 mm and a length of 100 mm is made so that the outermost circumference is a corrugated foil, and the flat foil and corrugated foil are brazed in a vacuum of 10 ⁻⁴ Torr. Join and
Furthermore, the outer periphery of the honeycomb body is covered with a soft rubber boot-shaped jig, immersed in a slurry of activated alumina, and pulled up.
A washcoat layer of activated alumina was formed only inside the metal honeycomb body. Then, after removing the coating jig, 0.5 g of platinum and 0.1 g of rhodium were carried, and
A metal honeycomb catalyst body shown in was obtained. An alumina fiber mat having a very high elasticity and a bulk density of 0.2 g / cm ³ was wound around the outer periphery of this honeycomb body, housed in a clamshell casing with two halves, and the casing was welded and mounted.

[Example 2] As shown in Fig. 1, a flat foil of heat-resistant steel having a thickness of 50 µm and a corrugated box were superposed and wound, and a diameter of 80 mm and a length of 100 mm so that the outermost periphery was corrugated foil. The honeycomb body of Fig. ⁴ was prepared, and the flat foil and the corrugated foil were brazed together in a vacuum of 10 ^-4 Torr, and further immersed in a slurry of activated alumina and pulled up. Was formed on the washcoat layer.
Then, carrying 0.5 g of platinum and 0.1 g of rhodium,
The metal honeycomb catalyst body shown in FIG. 3 (a) was obtained. The outer periphery of this honeycomb body has a very high elasticity and a bulk density of 0.2 g.
/ Cm ³ of alumina fibrous mat was wound and stored in a clam shell casing with two parts, and the casing was welded and installed.

[Example 3] Using the same metal honeycomb catalyst body as in Example 2, the inner surface of the casing was subjected to activated alumina washcoat treatment, and then the casing was welded and mounted.

[Comparative Example] As shown in FIG. 5, a flat foil having a thickness of 50 μm made of heat-resistant steel and a corrugated box were superposed and wound, and a 80 mm diameter and a 100 mm length were formed so that the outermost circumference was a corrugated foil. A honeycomb body was prepared and brazed in the same manner as in Example 1, a wash coat layer of activated alumina was formed only inside the metal honeycomb body, and 0.5 g of platinum and 0.1 g of rhodium were carried on the metal honeycomb catalyst body. Got Furthermore, Example 1
The same alumina fibrous mat as above was wound and mounted in the casing under the same conditions.

Table 1 shows the results of performance tests carried out on the products of the present invention and the comparative examples. The test condition is 20
Installed in the exhaust system of a 00cc gasoline engine, the gas entering 8
Hold for 5 minutes at 00 ℃, hold for 5 minutes at 150 ℃
It was set as a cold heat endurance condition in which 00 cycles were repeated.

[0024]

[Table 1]

[0025]

As described above, according to the present invention, since the outer peripheral surface of the honeycomb body is made of the corrugated material, the contact area with the honeycomb body and the holding member is increased, and the honeycomb body is damaged by the vibration of the engine or the shock during operation. It is possible to provide a metal carrier having an elastic holding member on the outer circumference of a honeycomb body where stable operation can be continued without causing a slippage. Furthermore, by forming a rough surface on the honeycomb body, the elastic holding material, or the inner surface of the casing by wash coating or the like, a more excellent metal carrier can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a honeycomb body of the present invention.

FIG. 2 is an explanatory cross-sectional view of a metal carrier of the present invention.

3 (a), (b) and (c) are explanatory views showing another example of the metal carrier of the present invention.

FIG. 4 is a cross-sectional explanatory view of a conventional metal carrier.

FIG. 5 is a perspective view of a conventional honeycomb body.

[Explanation of symbols]

 1: Metal carrier 2: Honeycomb body 2a: Flat plate (foil) 2b: Corrugated plate (foil) 3: Elastic holding member 4: Honeycomb body outermost peripheral surface 5: Casing 5a, 5b: Flange 6: Gap 7a, 7b, 7c: Rough surface 10: Honeycomb body 11: Outer cylinder

Claims (4)

[Claims] 1. A honeycomb body in which a flat plate made of a heat-resistant metal foil and a corrugated plate formed by corrugating the flat plate are overlapped and wound to form a spiral shape, and the outermost periphery of the honeycomb body is a corrugated plate. A metal carrier having an elastic holding member on the outer periphery of a honeycomb body, characterized in that the outermost corrugated sheet is covered with an elastic holding member. 2. The metal carrier having an elastic holding member on the outer periphery of the honeycomb body according to claim 1, wherein the outermost peripheral surface of the honeycomb body is formed into a rough surface. 3. The metal carrier having an elastic holding member on the outer periphery of the honeycomb body according to claim 1, wherein one or both of the inner surface of the casing and the surface of the elastic holding member are formed as a rough surface. 4. The metal carrier having an elastic holding member on the outer periphery of the honeycomb body according to claim 2, wherein the rough surface formed on the surface is wash coating.